Isolation And Structural Analysis Of Alkali-extracted Polysaccharides From Pleurotus Eryngii, Pleurotus Ostreatus And White Hypsizigus Marmoreus

Edible fungi(mushrooms)are well-known for their notable nutraceutical functions and medicinal properties.Polysaccharides including polysaccharide-protein complexes are major bioactive constituents of edible and medicinal fungi.This research project aims at the isolation and purification of alkaline-extracted polysaccharides from three edible mushrooms including Pleurotus eryngii,Pleurotus ostreatus and white Hypsizigus marmoreus cultivated in Northeastern China,and investigation of their molecular properties,chemical composition and structural information.The hot water extracted residues were extracted with 0.5 M NaOH solution and purified by gel permeation chromatography with Sepharose CL-6B and Sephadex G-50.The monosaccharide composition was analyzed by high performance liquid chromatography(HPLC).The molecular weight was analyzed by high performance gel permeation chromatography(HPGPC)on TSK G3000 column.Their structural features were investigated by Fourier transform-infrared(FT-IR)and nuclear magnetic resonance(NMR)spectroscopy.The crude alkali-extracted polysaccharides namely APEP(1.032%),APOP(1.67%)and AHMP(1.082%)were extracted from the basidiocarps of three species of mushrooms,including Pleurotus eryngii,Pleurotus ostreatus and White Hypsizigus marmoreus.The water soluble fractions APEP-S(82.6%),APOP-S(85.3%)and AMP-S(84.6%)were further isolated from crude polysaccharides by overnight water dissolution,centrifugation and lyophilization.The alkaline extracted water soluble polysaccharides APEP-S,APOP-S,and AHMP-S were further separated into two fractions on Sepharose CL-6B column,namely APEP-S-I(9.4%),APEP-S-II(54.3%),APOP-S-I(4.3%),APOP-S-II(56.6%),AHMP-S-I(4.3%)and AHMP-S-II(69.7%).The main fractions APEP-S-II,APOP-S-II and AHMP-S-II were further fractionated into two fractions on Sephadex G-50,namely APEP-S-IIa(80.7 % Glc,9.4% Man,8% Gal,and 1.8% GlcUA),APEP-S-IIb(97.8% Glc,1.9% Man,and 0.2% GlcUA),APOP-S-IIa(55.2% Glc,18.8% Gal,16.5% Man,5.7% GlcUA and 3.6% Ara),APOP-S-IIb(84.7% Glc,5.3% Gal,5.4 % Man and 4.52% GlcUA),AHMP-S-IIa,(62.2% Glc,19.8% Gal,9.2% Man,5.7% GlcUA and 2.9% Fuc)and AHMP-S-IIb(85.1% Glc,5.2% Gal,3.5% Man and 6% GlcUA).The Monosaccharide composition and HPGPC analysis indicated that APEP-S-IIa,APOP-S-IIa and AHMP-S-IIa were galactomannoglucan-type polysaccharides,with molecular weight of 3.2 × 104,4.5 × 104,2.5 × 104 Da,respectively.While APEP-S-IIb,APOP-S-IIb,and AHMP-S-IIb were predominantly glucan with a molecular weight of 4.5 × 103,5.5 × 103 and 5.4 × 103,respectively.The structural information were analyzed by FT-IR and 13 C NMR.The 13 C NMR indicated that APEP-S-IIa,APOP-S-IIa,AHMP-S-IIa were complex galactomannoglucans containing(1?6)and(1?3)linked ?-D-Glcp residues,(1?6)linked ?-D-Galp residues and terminal residues of ?-D-Manp,besides,APEP-S-IIa and APOP-S-IIa obtained from Pleurotus fungal polysaccharides contained ?6)-?-3-O-Me-Galp-(1? residues.However,APEP-S-IIb,APOP-S-IIb and AHMP-S-IIb are mostly showed similar results,contained typical signals were corresponded to ?(1?6)and ?(1?3)Dglucan.Thus,the investigation of alkaline-extracted water soluble polysaccharides from Pleurotus eryngii,Pleurotus ostreatus and white Hypsizigus marmoreus provides some information for the further study of fungal polysaccharides antitumor and immunomodulatory properties.